The present invention relates generally to the field of x-ray generation, and more particularly to the field of sealed x-ray tubes.
In conventional x-ray sources, such as those employed in laboratory applications, x-rays are produced by the acceleration of electrons from a cathode to a target. The resulting interaction between the electrons and the target causes the emission of x-rays. Different target material produce different spectra of x-rays.
Often, electron beams are focused near or on the targets to obtain the dimensions of the x-ray source. Unfortunately, the constant bombardment of the target with accelerated electrons results in target damage, in particular, melting and evaporation of the target material. This degradation limits the performance and operating lifetime of the x-ray source.
To address the target degradation problem, some systems employ a rotating anode source, which rotates the target at high speeds to distribute the region subject to bombardment across a larger area. However, rotating anode sources are complicated in design and are expensive to maintain. Moreover, the brilliance of rotating anode sources are not as high as the brilliance of a single-spot micro-focusing source.
Other x-ray sources have attempted to steer the electron beam to different target areas using magnetic fields. This approach, however, presents a number of disadvantages. For example, by changing the position of the electron beam relative to the target center, the x-ray source position is altered which may require reconfiguration of the optical components. Also, these systems depend heavily on the electronic components responsible for controlling the magnetic fields, which unnecessarily complicates the circuitry and maintenance of the x-ray source. Moreover, circuit stability directly influences the source position stability.
For certain laboratory applications, it is imperative that the x-rays generated by the source are emitted from the same position relative to the optical components located outside the source. If the position of the source of x-rays is constantly changing, then the optical configuration of the experimental system must also be constantly changing to compensate for changes in the source position, which is highly inefficient.
Given the foregoing, it is evident that there is a need for a single-spot micro-focusing x-ray source that has the advantages of long-life and durability associated with a rotating anode, but with the high-brilliance needed for advanced x-ray applications.